Carbon composition with hierarchical porosity, and methods of preparation

ABSTRACT

A method for fabricating a porous carbon material possessing a hierarchical porosity, the method comprising subjecting a precursor composition to a curing step followed by a carbonization step, the precursor composition comprising: (i) a templating component comprised of a block copolymer, (ii) a phenolic component, (iii) a dione component in which carbonyl groups are adjacent, and (iv) an acidic component, wherein said carbonization step comprises heating the precursor composition at a carbonizing temperature for sufficient time to convert the precursor composition to a carbon material possessing a hierarchical porosity comprised of mesopores and macropores. Also described are the resulting hierarchical porous carbon material, a capacitive deionization device in which the porous carbon material is incorporated, as well as methods for desalinating water by use of said capacitive deionization device.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. application Ser. No. 13/046,836filed on Mar. 14, 2011, the contents of which are incorporated herein byreference in their entirety.

This invention was made with government support under Prime Contract No.DE-AC05-00OR22725 awarded by the U.S. Department of Energy. Thegovernment has certain rights in the invention.

FIELD OF THE INVENTION

The present invention relates to the field of porous carbon materials,and more particularly, to such carbon materials containing a bimodal orhierarchical porosity.

BACKGROUND OF THE INVENTION

Porous carbon materials have long been used in capacitive deionization(CDI) technology. Capacitive deionization is increasingly beingconsidered for large-scale desalination operations because of its loweroperating costs. In CDI, salt water is made to flow between two porouselectrodes, typically made of carbon. When an electric field is appliedto render the electrodes opposite in polarity, positive ions becomeincorporated in the negatively-charged electrode while negative ionsbecome incorporated in the positively-charged electrode. The stored ionscan be subsequently released into a waste stream by reversing theelectrode polarities.

However, CDI technology is currently significantly hampered by thedifficulty in producing porous carbon films on a commercial scale in abatch-to-batch repeatable and uniform manner. The porous carbonsproduced until now (e.g., via resorcinol-formaldehyde reaction) leavelittle room for optimization and are generally hampered by the presenceof microporosity and/or broad mesopore size distributions. Moreover, theporous carbon films currently in use in CDI technology (e.g., asprepared by standard resorcinol-formaldehyde template methodology)generally provide a significantly lower than optimal kinetic adsorptioncharacteristic. Accordingly, there would be a particular benefit in aporous carbon material having improved adsorption and processingkinetics as applied to CDI technology, as well as a cost-effective andreliable method for its manufacture. There would be a further benefit ifsuch a method did not use formaldehyde, a known toxin and carcinogen.

SUMMARY OF THE INVENTION

In one aspect, the invention is directed to carbon materials possessinga hierarchical porosity, which can be, for example, a bimodal, trimodal,or higher multimodal porosity. These hierarchical porous carbonmaterials (i.e., “the porous carbon material”) are useful for a varietyof applications, particularly as capacitive deionization (CDI) electrodematerials. Other possible applications include, for example, gasseparation, chromatography, catalysis (e.g., as a support or activematerial), electrode materials (e.g., in batteries), andsupercapacitors. In particular embodiments, the hierarchical porouscarbon material considered herein is in the form of a film (i.e.,layer).

By virtue of the presence of larger pore sizes (i.e., macropores), thehierarchical porous carbon materials described herein provide at leastthe significant benefit of significantly alleviating the mass-transportlimitations encountered in porous carbon materials of the art. At thesame time, the inclusion of smaller pores (i.e., mesopores) in theseporous carbon materials maintains the effective removal of salt fromwater. Thus, the instant porous carbon materials can advantageouslydesalinate an equivalent volume of water in less time withoutcompromising salt removal efficiency.

In particular embodiments, the hierarchical porous carbon materialcontains mesopores having a size in the range of 2-50 nm and macroporeshaving a size of at least 75 nm. In further embodiments, thehierarchical porous carbon material contains mesopores having a size inthe range of 2-20 nm and macropores having a size in the range of100-500 nm. In further embodiments, the mesopores and/or macropores aresubstantially uniform in size. For example, in some embodiments, themesopores have a size characterized by an error margin of up to or lessthan ±2.5 nm. In other particular embodiments, at least a portion of theporous carbon material is amorphous (i.e., as opposed to graphitic).

In other aspects, the invention is directed to a more cost-effective andfacile method for fabricating hierarchical porous carbon materials.Methods are known in the art for producing hierarchical porous carbonmaterials. However, current methods are generally complex and employ amultiplicity of steps. Several of the known processes include, forexample, the incorporation of sacrificial particles that aresubsequently etched after curing and carbonization steps to form poresin the carbon material, as well as inclusion of secondary porogenspecies (for example, a glycol solvent). Furthermore, the methodologyknown in the art is generally not amenable to achieving batch-to-batchrepeatable, precise, and ordered sets of pore sizes in the carbonmaterial.

The method described herein is particularly advantageous in that anorganic precursor composition is applied to any of a variety ofsubstrates by simple means (e.g., spin-coating) and then carbonized toprovide a hierarchical porous carbon without requiring a subsequentetching step and without requiring a secondary porogen, such as aglycol, as commonly used in methods of the art. In a preferredembodiment, the method involves subjecting a precursor composition to acuring step followed by a carbonization step, the precursor compositionincluding: (i) a templating component that includes a block copolymer,(ii) a phenolic component, (iii) a dione component in which carbonylgroups are adjacent, and (iv) an acidic component, wherein thecarbonization step includes heating the precursor composition at acarbonizing temperature for sufficient time to convert the precursorcomposition to a carbon material possessing a hierarchical porosity. Thehierarchical porosity considered herein includes mesopores andmacropores.

The method described herein for producing hierarchical porous carbonmaterials has overcome many of the problems encountered in the art. Inparticular, the method described herein can produce a hierarchicalporous carbon material in fewer steps and without the use of sacrificialparticles or a secondary porogen, and without the use of toxicformaldehyde. Moreover, the method described herein can achieve thissimplified process without separate carbonization and pore-forming(e.g., etch) steps, i.e., the method described herein can achieve ahierarchical porous carbon material from the carbonization process step.

In yet other aspects, the invention is directed to a capacitivedeionization (CDI) device, as well as methods of using the CDI device inthe desalination of water. The CDI device includes at least first andsecond electrodes separated by a space, wherein at least one (or both,or all) of the electrodes includes the hierarchical porous carbonmaterial described above. As further discussed below, the instanthierarchical porous carbon materials, when used in a CDI device, havebeen found to provide superior ion uptake kinetics.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1. Nitrogen sorption isotherms and BJH pore size distribution ofhierarchical porous carbon produced from reaction of phloroglucinol andglyoxal.

FIG. 2. Raman spectrum of hierarchical porous carbon produced fromreaction of phloroglucinol and glyoxal.

FIG. 3. STEM images of hierarchical porous carbon produced from reactionof phloroglucinol and glyoxal.

FIGS. 4A, 4B. Capacitive deionization results for (a) a representativeresorcinol-formaldehyde mesoporous carbon of the art, and (b) thephloroglucinol-glyoxal hierarchical porous carbon produced herein.

DETAILED DESCRIPTION OF THE INVENTION

In one aspect, the invention is directed to porous carbon materialspossessing a hierarchical porosity that includes both mesopores andmacropores. As used herein, the term “hierarchical porosity” refers tothe presence of at least two different pore sizes in the porous carbonmaterial, i.e., at least one set of pores being mesoporous and at leastone set of pores being macroporous. The mesopores and macropores may bearranged, with respect to each other, in any of several different ways.For example, in some embodiments, the mesopores and macropores may beintermingled in an apparently disordered manner, i.e., without anyapparent organization. In other embodiments, at least one (or both) ofthe mesopores and macropores are arranged in an ordered (i.e.,patterned) manner, such as in a cubic or hexagonal arrangement.

As used herein and as understood in the art, the terms “mesopores” and“mesoporous” refer to pores having a size (i.e., pore diameter or poresize) of at least 2 nm and up to 50 nm, i.e., “between 2 and 50 nm”, or“in the range of 2-50 nm”. In different embodiments, the mesopores havea size of precisely or about 2 nm, 2.5 nm, 3 nm, 3.5 nm, 4 nm, 4.5 nm, 5nm, 5.5 nm, 6 nm, 6.5 nm, 7 nm, 7.5 nm, 8 nm, 8.5 nm, 9 nm, 9.5 nm, 10nm, 11 nm, 12 nm, 15 nm, 20 nm, 25 nm, 30 nm, 35 nm, 40 nm, 45 nm, or 50nm, or a particular size, or a variation of sizes, within a rangebounded by any two of these values.

As used herein, the terms “macropores” and “macroporous” refer to poreshaving a size of at least 75 nm. Generally, the macropores consideredherein have a size up to or less than 1 micron (1 μm). In differentembodiments, the macropores have a size of precisely, about, at least,or greater than 75 nm, 80 nm, 85 nm, 90 nm, 95 nm, 100 nm, 110 nm, 120nm, 130 nm, 140 nm, 150 nm, 160 nm, 170 nm, 180 nm, 190 nm, 200 nm, 225nm, 250 nm, 275 nm, 300 nm, 325 nm, 350 nm, 375 nm, 400 nm, 425 nm, 450nm, 475 nm, 500 nm, 550 nm, 600 nm, 650 nm, 700 nm, 750 nm, 800 nm, 850nm, 900 nm, 950 nm, or 1000 nm, or a particular size, or a variation ofsizes, within a range bounded by any two of these values.

As used herein, the term “about” generally indicates within ±0.5%, 1%,2%, 5%, or up to ±10% of the indicated value. For example, a pore sizeof about 10 nm generally indicates in its broadest sense 10 nm±10%,which indicates 9.0-11.0 nm. In addition, the term “about” can indicateeither a measurement error (i.e., by limitations in the measurementmethod), or alternatively, a variation or average in a physicalcharacteristic of a group (e.g., a population of pores).

In some embodiments, the porous carbon material possesses a microporouscomponent. The micropores can be beneficial in providing a significantlyincreased surface area. The microporous component can be included in anamount of, for example, about or at least 1%, 2%, 3%, 4%, 5%, 6%, 7%,8%, 9%, 10%, 15%, or 20%, or in an amount within a range bounded by anytwo of these values. As used herein, the terms “micropores” and“microporous” refer to pores having a diameter of less than 2 nm. Inparticular embodiments, the micropores have a size of precisely, about,up to, or less than 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4,1.5, 1.6, 1.7, 1.8, or 1.9 nm, or a particular size, or a variation ofsizes, within a range bounded by any two of these values.

In other embodiments, the porous carbon material possesses a substantialabsence of micropores. By a “substantial absence” of micropores isgenerally meant that no more than 1%, 0.5%, or 0.1% of the total porevolume, or none of the pore volume, can be attributed to the presence ofmicropores.

The pores of the carbon material can also possess a level of uniformity,i.e., in pore size and/or pore shape. For example, in differentembodiments, the pores of the carbon material may possess an averagepore diameter corresponding to any of the diameters exemplified above,subject to a degree of variation of no more than, for example, ±10 nm,±8 nm, ±6, nm, ±5 nm, ±4 nm, ±3 nm, ±2.5 nm, ±2 nm, ±1.5 nm, ±1 nm,±0.5, ±0.4, ±0.3, ±0.2, or ±0.1 nm. Alternatively, the pore sizeuniformity may be indicated by being within a percentage from a targetpore size, e.g., within 25%, 20%, 15%, 10%, 5%, 2% 1%, or 0.5% of atarget pore size. In some embodiments, all of the pores aresubstantially uniform in size, while in other embodiments, a portion ofthe pores (e.g., the mesopores or the macropores) are substantiallyuniform in size.

The pores can have any suitable wall thickness. For example, indifferent embodiments, the wall thickness can be precisely, about, atleast, or less than, for example, 1 nm, 2 nm, 3 nm, 4 nm, 5 nm, 6 nm, 7nm, 8 nm, 9 nm, 10 nm, 11 nm, 12 nm, 15 nm, 18 nm, 20 nm, 25 nm, 30 nm,40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, 125 nm, 150 nm, 175nm, 200 nm, 250 nm, 300 nm, 350 nm, 400 nm, 450 nm, or 500 nm, or a wallthickness within a range bounded by any two of these values. Theforegoing exemplary wall thicknesses can be for all pores, or for aportion of the pores, e.g., only for mesopores, macropores, ormicropores.

The porous carbon material typically possesses a BET surface area ofabout or at least 50, 100, 200, 300, 400, 450, 500, 550, 600, 650, 700,750, 800, 900, 1000, or 1500 m²/g, or a surface area within a rangebounded by any two of these values. The porous carbon material maypossess a total pore volume of precisely, about, or at least, forexample, 0.2 cm³/g, 0.25 cm³/g, 0.3 cm³/g, 0.35 cm³/g, 0.4 cm³/g, 0.45cm³/g, 0.5 cm³/g, 0.55 cm³/g, 0.6 cm³/g, 0.65 cm³/g, 0.7 cm³/g, 0.75cm³/g, 0.8 cm³/g, 0.9 cm³/g, 1 cm³/g, 1.1 cm³/g, 1.2 cm³/g, 1.3 cm³/g,1.4 cm³/g, 1.5 cm³/g, 1.6 cm³/g, 1.7 cm³/g, 1.8 cm³/g, 1.9 cm³/g, 2cm³/g, 2.1 cm³/g, 2.2 cm³/g, 2.3 cm³/g, 2.4 cm³/g, 2.5 cm³/g, 2.6 cm³/g,2.7 cm³/g, 2.8 cm³/g, 2.9 cm³/g, or 3.0 cm³/g, or a pore volume within arange bounded by any two of these values.

Preferably, at least a portion of the porous carbon material isamorphous rather than graphitic. Generally, an amorphous portion of thecarbon material includes micropores, whereas micropores are generallyabsent from graphitic portions. As discussed above, the presence ofmicropores can provide certain advantages. In different embodiments,precisely, about, or at least 20%, 30%, 40%, 50%, 60%, 70%, 80%, 85%, or90% of the porous carbon material is amorphous, wherein it is understoodthat the remaining portion of the carbon material is graphitic oranother phase of carbon (e.g., glassy or vitreous carbon). In particularembodiments, the porous carbon material is no more than, or less than,25%, 20%, 15%, 10%, 5%, 2%, or 1% graphitic. In some embodiments, all(e.g., about or precisely 100%) or substantially all (for example,greater than 90%, 95%, 98%, or 99%) of the porous carbon material isnon-graphitic, and may be instead, for example, amorphous or glassycarbon.

The porous carbon material can be in any suitable form, e.g., as rods,cubes, or sheets, depending on the application. In particularembodiments, the porous carbon material is in the form of a film. Thefilm can have any suitable thickness, typically no more than 5millimeters (5 mm). In different embodiments, the film may preferablyhave a thickness of precisely, about, up to, at least, or less than, forexample, 5 nm, 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 100 nm, 200 nm, 300nm, 400 nm, 500 nm, 600 nm, 700 nm, 800 nm, 900 nm, 1.0 μm, 1.2 μm, 1.5μn, 2.0 μm, 2.5 μn, 3.0 μm, 4.0 μm, 5.0 μm, 10 μm, 20 μm, 30 μm, 40 μm,60 μm, 70 μm, 80 μm, 90 μm, 100 μm, 150 μm, 200 μm, 250 μm, 300 μm, 350μm, 400 μm, 450 μm, 500 μm, 600 μm, 700 μm, 800 μm, 900 μm, or 1000 μm,or a thickness within a range bounded by any two of these values.

The porous carbon film may also function as part of a compositematerial, wherein the porous carbon film either overlays, underlies, oris sandwiched between one or more layers of another material. The othermaterial may be porous or non-porous, and can be composed of, forexample, a metal, metal alloy, ceramic (e.g., silica, alumina, or ametal oxide), organic or inorganic polymer, or composite or hybridthereof, depending on the application. In particular embodiments, theporous carbon film functions as a coating on an electrically-conductingsubstrate suitable as an electrode. In further particular embodiments,the electrically-conducting substrate is, or includes, a carbonmaterial, such as graphite. In other embodiments, the porous carbon filmis monolithic (i.e., not disposed on a substrate).

In another embodiment, the porous carbon material is in the form ofparticles. In different embodiments, the particles have a sizeprecisely, about, up to, or less than, for example, 5 nm, 10 nm, 20 nm,30 nm, 40 nm, 50 nm, 100 nm, 200 nm, 500 nm, 1 μm, 2 μm, 5 μm, 10 μm, 50μm, 100 μm, 500 μm, or 1000 μm, or a size within a range bounded by anytwo of these values.

In another aspect, the invention is directed to methods for fabricatinga hierarchical porous carbon material, such as any of the hierarchicalporous carbon materials described above. The method first involvesproviding (i.e., preparing or otherwise obtaining in prepared form) aprecursor composition to be subjected to a curing step followed by acarbonization step in order to produce a porous carbon material of theinvention. The precursor composition includes at least the followingcomponents: (i) a templating component that contains (or includes) ablock copolymer, (ii) a phenolic component (i.e., one or more phenoliccompounds), (iii) a dione component (i.e., one or more dione compounds)in which carbonyl groups are adjacent, and (iv) an acidic component. Insome embodiments, the precursor composition contains only the foregoingfour components (i.e., any other compound or material not within thescope of the foregoing components is excluded).

The combination of phenolic component and dione component is hereinreferred to as the “polymer precursor” or “polymer precursorcomponents”. These two components, when properly reacted and cured (asfurther discussed below), produce a polymer that is subsequentlycarbonized during a carbonization step. Hence, the polymer functions asa carbon precursor. In contrast, the templating component (i.e., blockcopolymer) functions to organize the polymer precursor materials in anordered (i.e., patterned) arrangement before the carbonization step.During carbonization, the block copolymer is typically completelyvolatized into gaseous byproducts, and thereby, generally does notcontribute to the carbon content. However, the volatile gases serve theimportant role of creating at least the mesopores in the carbonstructure during the carbonization step. The mechanism by which thehierarchical porous structure, including macropores, is produced, is notcurrently understood in much detail. It is believed that, while theblock copolymer is largely responsible for producing mesopores, thephenolic compound, dione compound, or combination thereof (orcombination of any of these compounds with the block copolymer) isresponsible for the hierarchical porosity.

The templating component includes one or more block copolymers. Theblock copolymer preferably has the ability to establish selectiveinteractions with the polymer precursor components in such a manner thatan organized network of interactions between the block copolymer andpolymer precursor components results. Typically, such selectiveinteractions occur when at least two different segments of the blockcopolymer differ in hydrophobicity (or hydrophilicity). Generally, ablock copolymer that can self-organize based on hydrophobic or othervariations will be suitable as a templating component herein. Such blockcopolymers typically form periodic structures by virtue of selectiveinteractions between like domains, i.e., between hydrophobic domains andbetween hydrophilic domains. In some embodiments, the templatingcomponent includes only one or more block copolymers, i.e., excludesother compounds and materials that are not block copolymers. In someembodiments, the block copolymer includes one or more ionic groups. Inother embodiments, the block copolymer is non-ionic.

As used herein, a “block copolymer” is a polymer containing two or morechemically distinct polymeric blocks (i.e., sections or segments). Thecopolymer can be, for example, a diblock copolymer (e.g., A-B), triblockcopolymer (e.g., A-B-C), tetrablock copolymer (e.g., A-B-C-D), or higherblock copolymer, wherein A, B, C, and D represent chemically distinctpolymeric segments. The block copolymer is preferably not completelyinorganic, and more preferably, completely organic (i.e., carbon-based)in order that the block copolymer is at least partially capable ofvolatilizing during the carbonization step. The block copolymer istypically linear; however, branched (e.g., glycerol branching units) andgrafted block copolymer variations are also contemplated herein.Preferably, the block copolymer contains polar groups capable ofinteracting (e.g., by hydrogen or ionic bonding) with the phenoliccomponent and/or dione component. Some of the groups preferably locatedin the block copolymer that can provide a favorable interactive bondwith phenolic and/or carbonyl groups include, for example, ether,hydroxy, amino, imino, and carbonyl groups. For this reason, the blockcopolymer is preferably not a complete hydrocarbon such asstyrene-butadiene, although it may be desirable in some situations toinclude a generally hydrophobic polymer or block copolymer with a polarinteractive block copolymer to suitably modify or enhance the organizingor patterning characteristics and ability of the polar block copolymer.For analogous reasons, a generally hydrophilic polymer (e.g., apolyalkylene oxide, such as polyethylene oxide or polypropylene oxide)or generally hydrophilic block copolymer may be included with the polarinteractive block copolymer. In other embodiments, such generallyhydrophobic or hydrophilic polymers or copolymers are excluded.

Some examples of classes of block copolymers suitable as templatingagents include those containing segments of polyacrylate orpolymethacrylate (and esters thereof), polystyrene, polyethyleneoxide,polypropyleneoxide, polyethylene, polyacrylonitrile, polylactide, andpolycaprolactone. Some specific examples of templating block copolymersinclude polystyrene-b-poly(methylmethacrylate) (i.e., PS-PMMA),polystyrene-b-poly(acrylic acid) (i.e., PS-PAA),polystyrene-b-poly(4-vinylpyridine) (i.e., PS-P4VP),polystyrene-b-poly(2-vinylpyridine) (i.e., PS-P2VP),polyethylene-b-poly(4-vinylpyridine) (i.e., PE-P4VP),polystyrene-b-polyethyleneoxide (i.e., PS-PEO),polystyrene-b-poly(4-hydroxystyrene),polyethyleneoxide-b-polypropyleneoxide (i.e., PEO-PPO),polyethyleneoxide-b-poly(4-vinylpyridine) (i.e., PEO-P4VP),polyethylene-b-polyethyleneoxide (i.e., PE-PEO),polystyrene-b-poly(D,L-lactide),polystyrene-b-poly(methylmethacrylate)-b-polyethyleneoxide (i.e.,PS-PMMA-PEO), polystyrene-b-polyacrylamide,polystyrene-b-polydimethylacrylamide (i.e., PS-PDMA),polystyrene-b-polyacrylonitrile (i.e., PS-PAN), andpolyethyleneoxide-b-polyacrylonitrile (i.e., PEO-PAN). In someembodiments, one or more of any of the foregoing classes or specifictypes of copolymers are excluded.

In particular embodiments, the block copolymer is a diblock or triblockcopolymer containing two or three segments, respectively, which havealkyleneoxide compositions, particularly wherein the alkyleneoxide isselected from polyethyleneoxide (PEO) and polypropyleneoxide (PPO)segments. In more particular embodiments, the block copolymer is analkyleneoxide triblock copolymer, such as a poloxamer (i.e. Pluronic® orLutrol® polymer) according to the general formula(PEO)_(a)-(PPO)_(b)-(PEO)_(c), wherein PEO is a polyethylene oxide blockand PPO is a polypropylene block (i.e., —CH₂CH(CH₃)O— or —CH(CH₃)CH₂O—),and the subscripts a, b, and c represent the number of monomer units ofPEO and PPO, as indicated. Typically, a, b, and c are each at least 2,and more typically, at least 5, and typically up to a value of 100, 120,or 130. Subscripts a and c are often of equal value in these types ofpolymers. In different embodiments, a, b, and c can independently have avalue of about, or at least, or up to 10, 20, 30, 40, 50, 60, 70, 80,90, 100, 120, 130, 140, 150, 160, 180, 200, 220, 240, or any particularrange established by any two of these exemplary values.

In one embodiment, a and c subscripts are each less than b, i.e., thehydrophilic PEO block is shorter on each end than the hydrophobic PPOblock. For example, in different embodiments, a, b, and c can eachindependently have a value of 2, 5, 7, 10, 12, 15, 20, 25, 30, 35, 40,45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 110, 120, 130, 140,150, or 160, or any range delimited by any two of these values, providedthat a and c values are each less than b. Furthermore, in differentembodiments, it can be preferred for the a and c values to be less thanb by a certain number of units, e.g., by 2, 5, 7, 10, 12, 15, 20, 25,30, 35, 40, 45, or 50 units, or any range therein. Alternatively, it canbe preferred for the a and c values to be a certain fraction orpercentage of b (or less than or greater than this fraction orpercentage), e.g., about 10%, 20%, 25%, 30, 33%, 40%, 50%, 60%, 70%,75%, 80%, 85%, 90%, or any range delimited by any two of these values.

In another embodiment, a and c subscripts are each greater than b, i.e.,the hydrophilic PEO block is longer on each end than the hydrophobic PPOblock. For example, in different embodiments, a, b, and c can eachindependently have a value of 2, 5, 7, 10, 12, 15, 20, 25, 30, 35, 40,45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 110, 120, 130, 140,150, or 160, or any range delimited by any two of these values, providedthat a and c values are each greater than b. Furthermore, in differentembodiments, it can be preferred for the a and c values to be greaterthan b by a certain number of units, e.g., by 2, 5, 7, 10, 12, 15, 20,25, 30, 35, 40, 45, or 50 units, or any range therein. Alternatively, itcan be preferred for the b value to be a certain fraction or percentageof a and c values (or less than or greater than this fraction orpercentage), e.g., about 10%, 20%, 25%, 30, 33%, 40%, 50%, 60%, 70%,75%, 80%, 85%, 90%, or any range delimited by any two of these values.

In different embodiments, the poloxamer preferably has a minimum averagemolecular weight of at least 500, 800, 1000, 1200, 1500, 2000, 2500,3000, 3500, 4000, or 4500 g/mole, and a maximum average molecular weightof 5000, 5500, 6000, 6500, 7000, 7500, 8000, 8500, 9000, 9500, 10,000,12,000, 15,000, or 20,000 g/mole, wherein a particular range can beestablished between any two of the foregoing values, and particularly,between any two the minimum and maximum values. The viscosity of thepolymers is generally at least 200, 250, 300, 350, 400, 450, 500, 550,600, or 650 centipoise (cps), and generally up to 700, 800, 900, 1000,1500, 2000, 2500, 3000, 3500, 4000, 4500, 5000, 5500, 6000, 6500, 7000,or 7500 cps, or any particular range established between any two of theforegoing values.

The following table lists several exemplary poloxamer polymersapplicable to the present invention.

TABLE 1 Some exemplary poloxamer polymers Generic Pluronic ® ApproximateApproximate Approximate Name Name value of a value of b value of cPoloxamer Pluronic L-31 2 16 2 101 Poloxamer Pluronic L-35 11 16 11 105Poloxamer Pluronic F-38 46 16 46 108 Poloxamer — 5 21 5 122 PoloxamerPluronic L-43 7 21 7 123 Poloxamer Pluronic L-44 11 21 11 124 PoloxamerPluronic L-61 3 30 3 181 Poloxamer Pluronic L-62 8 30 8 182 Poloxamer —10 30 10 183 Poloxamer Pluronic L-64 13 30 13 184 Poloxamer PluronicP-65 19 30 19 185 Poloxamer Pluronic F-68 75 30 75 188 Poloxamer — 8 358 212 Poloxamer — 24 35 24 215 Poloxamer Pluronic F-77 52 35 52 217Poloxamer Pluronic L-81 6 39 6 231 Poloxamer Pluronic P-84 22 39 22 234Poloxamer Pluronic P-85 27 39 27 235 Poloxamer Pluronic F-87 62 39 62237 Poloxamer Pluronic F-88 97 39 97 238 Poloxamer Pluronic L-92 10 4710 282 Poloxamer — 21 47 21 284 Poloxamer Pluronic F-98 122 47 122 288Poloxamer Pluronic L-101 7 54 7 331 Poloxamer Pluronic P-103 20 54 20333 Poloxamer Pluronic P-104 31 54 31 334 Poloxamer Pluronic P-105 38 5438 335 Poloxamer Pluronic F-108 128 54 128 338 Poloxamer Pluronic L-1216 67 6 401 Poloxamer Pluronic P-123 21 67 21 403 Poloxamer PluronicF-127 98 67 98 407

As known in the art, the names of the poloxamers and Pluronics (as givenabove) contain numbers that provide information on the chemicalcomposition. For example, the generic poloxamer name contains threedigits, wherein the first two digits×100 indicates the approximatemolecular weight of the PPO portion and the last digit×10 indicates theweight percent of the PEO portion. Accordingly, poloxamer 338 possessesa PPO portion of about 3300 g/mole molecular weight, and 80 wt % PEO. Inthe Pluronic name, the letter indicates the physical form of theproduct, i.e., L=liquid, P=paste, and F=solid, i.e., flake. The firstdigit, or two digits for a three-digit number, multiplied by 300,indicates the approximate molecular weight of the PPO portion, while thelast digit×10 indicates the weight percent of the PEO portion. Forexample, Pluronic® F-108 (which corresponds to poloxamer 338) indicatesa solid form composed of about 3,000 g/mol of the PPO portion and 80 wt% PEO.

Numerous other types of copolymers containing PEO and PPO blocks arepossible, all of which are applicable herein. For example, the blockcopolymer can also be a reverse poloxamer of general formula(PPO)_(a)-(PEO)_(b)-(PPO)_(c), wherein all of the details consideredabove with respect to the regular poloxamers (e.g., description of a, b,and c subscripts, and all of the other exemplary structuralpossibilities) are applicable by reference herein for the reversepoloxamers.

In another variation, the block copolymer contains a linking diaminegroup (e.g., ethylenediamine, i.e., EDA) or triamine group (e.g.,melamine). Some examples of such copolymers include the Tetronics®(e.g., PEO-PPO-EDA-PPO-PEO) and reverse Tetronics® (e.g.,PPO-PEO-EDA-PEO-PPO).

The phenolic component is or includes any phenolic compound that canreact by a condensation reaction with a carbonyl-containing compound(and more particularly, a dione compound, as described herein) underacidic conditions. Typically, any compound that includes at least onehydroxy group bound to an aromatic ring (typically, a phenyl ring) issuitable for the present invention as a phenolic compound. In someembodiments, the phenolic component includes only one or more phenoliccompounds, i.e., excludes other compounds and materials that are notphenolic.

In one embodiment, the phenolic compound contains one phenolic hydroxygroup (i.e., one hydroxy group bound to a six-membered aromatic ring).Some examples of such compounds include phenol, the halophenols, theaminophenols, the hydrocarbyl-substituted phenols (wherein “hydrocarbyl”includes, e.g., straight-chained, branched, or cyclic alkyl, alkenyl, oralkynyl groups typically containing from 1 to 6 carbon atoms, optionallysubstituted with one or more oxygen or nitrogen atoms),hydrocarbyl-unsubstituted phenols, naphthols (e.g., 1- or 2-naphthol),nitrophenols, hydroxyanisoles, hydroxybenzoic acids, fatty acidester-substituted or polyalkyleneoxy-substituted phenols (e.g., on the 2or 4 positions with respect to the hydroxy group), phenols containing anazo linkage (e.g., p-hydroxyazobenzene), and phenolsulfonic acids (e.g.,p-phenolsulfonic acid). Some general subclasses of halophenols includethe fluorophenols, chlorophenols, bromophenols, and iodophenols, andtheir further sub-classification as, for example, p-halophenols (e.g.,4-fluorophenol, 4-chlorophenol, 4-bromophenol, and 4-iodophenol),m-halophenols (e.g., 3-fluorophenol, 3-chlorophenol, 3-bromophenol, and3-iodophenol), o-halophenols (e.g., 2-fluorophenol, 2-chlorophenol,2-bromophenol, and 2-iodophenol), dihalophenols (e.g.,3,5-dichlorophenol and 3,5-dibromophenol), and trihalophenols (e.g.,3,4,5-trichlorophenol, 3,4,5-tribromophenol, 3,4,5-trifluorophenol,3,5,6-trichlorophenol, and 2,3,5-tribromophenol). Some examples ofaminophenols include 2-, 3-, and 4-aminophenol, and 3,5- and2,5-diaminophenol. Some examples of nitrophenols include 2-, 3-, and4-nitrophenol, and 2,5- and 3,5-dinitrophenol. Some examples ofhydrocarbyl-substituted phenols include the cresols, i.e., methylphenolsor hydroxytoluenes (e.g., o-cresol, m-cresol, p-cresol), the xylenols(e.g., 3,5-, 2,5-, 2,3-, and 3,4-dimethylphenol), the ethylphenols(e.g., 2-, 3-, and 4-ethylphenol, and 3,5- and 2,5-diethylphenol),n-propylphenols (e.g., 4-n-propylphenol), isopropylphenols (e.g.,4-isopropylphenol), butylphenols (e.g., 4-n-butylphenol,4-isobutylphenol, 4-t-butylphenol, 3,5-di-t-butylphenol,2,5-di-t-butylphenol), hexylphenols, octyl phenols (e.g.,4-n-octylphenol), nonylphenols (e.g., 4-n-nonylphenol), phenylphenols(e.g., 2-phenylphenol, 3-phenylphenol, and 4-phenylphenol), andhydroxycinnamic acid (p-coumaric acid). Some examples of hydroxyanisolesinclude 2-methoxyphenol, 3-methoxyphenol, 4-methoxyphenol,3-t-butyl-4-hydroxyanisole (e.g., BHA), and ferulic acid. Some examplesof hydroxybenzoic acids include 2-hydroxybenzoic acid (salicylic acid),3-hydroxybenzoic acid, 4-hydroxybenzoic acid, and their organic acidesters (e.g., methyl salicylate and ethyl-4-hydroxybenzoate).

In another embodiment, the phenolic compound contains two phenolichydroxy groups. Some examples of such compounds include catechol,resorcinol, hydroquinone, the hydrocarbyl-linked bis-phenols (e.g.,bis-phenol A, methylenebisphenol, and 4,4′-dihydroxystilbene),4,4′-biphenol, the halo-substituted diphenols (e.g., 2-haloresorcinols,3-haloresorcinols, and 4-haloresorcinols, wherein the halo group can befluoro, chloro, bromo, or iodo), the amino-substituted diphenols (e.g.,2-aminoresorcinol, 3-aminoresorcinol, and 4-aminoresorcinol), thehydrocarbyl-substituted diphenols (e.g., 2,6-dihydroxytoluene, i.e.,2-methylresorcinol; 2,3-, 2,4-, 2,5-, and 3,5-dihydroxytoluene,1-ethyl-2,6-dihydroxybenzene, caffeic acid, and chlorogenic acid), thenitro-substituted diphenols (e.g., 2- and 4-nitroresorcinol),dihydroxyanisoles (e.g., 3,5-, 2,3-, 2,5-, and 2,6-dihydroxyanisole, andvanillin), dihydroxybenzoic acids (e.g., 3,5-, 2,3-, 2,5-, and2,6-dihydroxybenzoic acid, and their alkyl esters, and vanillic acid),and phenolphthalein.

In another embodiment, the phenolic compound contains three phenolichydroxy groups. Some examples of such compounds include phloroglucinol(1,3,5-trihydroxybenzene), pyrogallol (1,2,3-trihydroxybenzene),1,2,4-trihydroxybenzene, 5-chloro-1,2,4-trihydroxybenzene, resveratrol(trans-3,5,4′-trihydroxystilbene), the hydrocarbyl-substitutedtriphenols (e.g., 2,4,6-trihydroxytoluene, i.e., methylphloroglucinol,and 3,4,5-trihydroxytoluene), the halogen-substituted triphenols (e.g.,5-chloro-1,2,4-trihydroxybenzene), the carboxy-substituted triphenols(e.g., 3,4,5-trihydroxybenzoic acid, i.e., gallic acid or quinic acid,and 2,4,6-trihydroxybenzoic acid), the nitro-substituted triphenols(e.g., 2,4,6-trihydroxynitrobenzene), and phenol-formaldehyde resoles ornovolak resins containing three phenol hydroxy groups.

In yet another embodiment, the phenolic compound or material containsmultiple (i.e., greater than three) phenolic hydroxy groups. Someexamples of such compounds include tannin (e.g., tannic acid), tanninderivatives (e.g., ellagotannins and gallotannins), phenol-containingpolymers (e.g., poly-(4-hydroxystyrene)), phenol-formaldehyde resoles ornovolak resins containing at least four phenol groups (e.g., at least 4,5, or 6 phenol groups), quercetin, ellagic acid, and tetraphenol ethane.

In some embodiments, one, two, or more of any of the classes or specifictypes of phenolic compounds described above are excluded from thephenolic component. In particular embodiments, the phenolic compound ismonocyclic (i.e., contains a phenyl ring not fused or connected toanother ring) and contains two or three phenolic hydroxy groups. Forexample, in some embodiments, the phenolic component is, or includes,resorcinol and/or phloroglucinol (i.e., 1,3,5-trihydroxybenzene).

The dione component includes one or more compounds containing carbonylgroups that are adjacent. The carbonyl groups can be, for example, ketoand/or aldehydic groups. By being “adjacent” is meant that the twocarbonyl groups are in close enough proximity to be jointly engaged in asingle hydrogen bonding interaction (e.g., a hydrogen atom engaging bothcarbonyl group oxygens), or similarly, close enough to be involved in atautomeric interaction, as understood in the art and as described infurther detail below. Generally, for purposes of the invention, carbonylgroups are considered adjacent if they are vicinal (i.e., are connectedby a bond between carbonyl carbon atoms) or if they are attached to thesame or adjacent (i.e., 1,2 or ortho) ring carbon atoms in a cyclicstructure, particularly an aromatic cyclic, bicyclic, or higherpolycyclic structure.

In a first set of embodiments, the dione component includes one or morevicinal dione compounds. In particular embodiments, the vicinal dionecompound has the following chemical structure:

In formula (1), R¹ and R² are independently selected from hydrogen atomand hydrocarbon groups. In particular embodiments, the hydrocarbongroups considered herein contain precisely, at least, or up to one, two,three, four, five, or six carbon atoms. In some embodiments, thehydrocarbon groups contain only carbon and hydrogen atoms. In otherembodiments, the hydrocarbon groups may further include one or moreoxygen atoms inserted between carbon atoms, or can have one or morehydrogen atoms substituted with one or more heteroatom-containinggroups, such as hydroxy, halogen atom (e.g., F, Cl, or Br), ether (e.g.,methoxy, ethoxy, epoxide, and/or glycidyl), carboxylic acid, carboxylicester, and/or amido groups. In some embodiments, one or both hydrocarbongroups are saturated. The saturated hydrocarbon groups can bestraight-chained (e.g., methyl, ethyl, n-propyl, n-butyl, n-pentyl, andn-hexyl), or branched (e.g., isopropyl, isobutyl, sec-butyl, t-butyl,isopentyl, and neopentyl), or cyclic (e.g., cyclopropyl, cyclobutyl,cyclopentyl, and cyclohexyl). In other embodiments, one or bothhydrocarbon groups are unsaturated. The unsaturated hydrocarbon groupscan be straight-chained (e.g., vinyl or allyl), or branched (e.g.,2-methylallyl), or cyclic (e.g., cyclopentenyl, cyclopentadienyl,cyclohexenyl, and phenyl).

In some embodiments of Formula (1), R¹ and R² are hydrogen atoms, thuscorresponding to glyoxal, i.e., HC(O)C(O)H (i.e., 1,2-ethandial). Inother embodiments of Formula (1), one of R¹ and R² is a hydrogen atomwhile another of R¹ and R² is a hydrocarbon group, thus corresponding tovicinal aldehyde-ketone compounds. Some examples of vicinalaldehyde-ketone compounds include 2-oxopropanal (i.e., methylglyoxal,also known as pyruvaldehyde), 2-oxobutanal (i.e., ethylglyoxal),2-oxopentanal (i.e., n-propylglyoxal), 2-oxohexanal,3-methyl-2-oxobutanal (i.e., isopropylglyoxal), 3-methyl-2-oxopentanal,4-methyl-2-oxopentanal (i.e., isobutylglyoxal), 2-oxobut-3-enal, and2-cyclopropyl-2-oxoacetaldehyde. In yet other embodiments of Formula(1), R¹ and R² are both hydrocarbon groups, thus corresponding tovicinal diketone compounds. In the vicinal diketone compounds, R¹ and R²can be independently selected from any of the types of hydrocarbongroups described above. Some examples of vicinal ketone compoundsinclude 2,3-butadione (i.e., diacetyl), 2,3-pentanedione (i.e.,ethylmethylglyoxal), 2,3-hexanedione (i.e., methylpropylglyoxal),3,4-hexanedione (i.e., diethylglyoxal), 2,3-heptanedione,3,4-heptanedione, 2,3-octanedione, 3,4-octanedione, 4,5-octanedione(dipropylglyoxal), pent-4-ene-2,3-dione, and hexa-1,5-diene-3,4-dione.

In some embodiments, R¹ and R² in Formula (1) are not interconnected. Inother embodiments, R¹ and R² are interconnected as a cyclic structure.Typically, the R¹-R² interconnection contains precisely or at leastthree or four ring carbon atoms. The ring carbon atoms in the R¹-R²interconnection may or may not also have one or more hydrogen atomstherein substituted by one or more hydrocarbon groups, typically alkygroups containing one, two, or three carbon atoms. Some examples ofdione compounds wherein R¹ and R² in Formula (1) are interconnectedinclude cyclopentane-1,2-dione, 3,5-dimethylcyclopentane-1,2-dione,3,4,4-trimethylcyclopentane-1,2-dione, cyclohexane-1,2-dione,cycloheptane-1,2-dione, cyclohex-4-ene-1,2-dione, andcyclohexa-3,5-diene-1,2-dione.

In a second set of embodiments, the dione component has two carbonylgroups attached to adjacent (i.e., 1,2 or ortho) ring carbon atoms in acyclic structure. In particular embodiments, such a dione compound hasthe following chemical structure:

In Formula (2), the cyclic group represents a saturated or unsaturatedmonocyclic, bicyclic, or tricyclic group. The cyclic group can besaturated or unsaturated. The cyclic group may alternatively bealiphatic or aromatic. As defined herein, a monocyclic group includes asingle ring not fused or bonded to another ring. A bicyclic groupcontains two rings either fused or connected by a bond. A tricyclicgroup contains three rings either fused or connected by bonds.Typically, the monocyclic group contains precisely or at least four,five, or six ring carbon atoms. Bicyclic groups may contain precisely orat least, for example, eight, nine, or ten ring carbon atoms. Tricyclicgroups may contain precisely or at least, for example, thirteen orfourteen ring carbon atoms. In some embodiments, the cyclic groupcontains only carbon and hydrogen atoms (i.e., is carbocyclic). In otherembodiments, the cyclic group includes one or more ring heteroatomsselected from oxygen, nitrogen, and sulfur (i.e., is heterocyclic). Thecyclic group may or may not also have one or more hydrogen atomssubstituted with one or more hydrocarbon groups (e.g., alkyl groups ofone to three carbon atoms) and/or one or more heteroatom-containinggroups (e.g., selected from hydroxy, methoxy, ethoxy, amino,carboxamido, keto, and aldehyde groups).

Some examples of saturated monocyclic groups in Formula (2) includecyclopentylene and cyclohexylene groups, thereby resulting incyclopentane-1,2-dicarboxaldehyde and cyclohexane-1,2-dicarboxaldehyde,respectively, for the structure in Formula (2). Some examples ofunsaturated monocyclic groups include phenylene, cyclopentadienyl (e.g.,2,3-diyl), and furan-2,5-diyl, thereby resulting in1,2-benzenedialdehyde (i.e., phthalaldehyde),cyclopenta-1,3-diene-2,3-dicarboxaldehyde, andfuran-2,5-dicarboxaldehyde, respectively, for the structure in Formula(2). Some examples of bicyclic and tricyclic groups include naphthalenyl(e.g., 2,3-diyl) and anthracenyl (e.g., 2,3-diyl), thereby resulting in,for example, naphthalene-2,3-dicarboxaldehyde andanthracene-2,3-dicarboxaldehyde, respectively, for the structure inFormula (2).

In Formulas (1) and (2), the close proximity of the carbonyl groupspermits the carbonyl groups to engage in a simultaneous hydrogen bondinginteraction with protic species (in particular, phenol groups) presentin the precursor composition. More particularly, the close proximity ofthe carbonyl groups is believed to form a hydrogen-bonded enolicintermediate after one of the carbonyl groups is electrophilicallyattacked by an active phenol carbon. The foregoing concept is depictedas follows, with phloroglucinol and glyoxal as exemplary phenolic anddione compounds (wherein the hydrogen bond is indicated by a dashedbond):

Without being bound by any theory, it is believed that formation of thishydrogen bond causes a moderation in reactivity of the remainingcarbonyl group. This moderating effect is believed to be at least partlyresponsible for the hierarchical porous feature of the carbon materialsproduced herein. In particular, by forming the hydrogen bond, it isbelieved that the reactivity of at least the second aldehyde group(i.e., the one not connected to the phenol group) is muted, thusaffecting its reactivity. This effect could result in, or promote, ahierarchical structure by affecting how the phenolic groups interlink.The muted reactivity could, for example, inhibit or prohibit theformation of a bond to the second aldehyde or provide a reactive siteafter the first round of reactions, i.e., result in a delayed reaction.The delayed reaction could constrain the carbon polymer such that duringannealing the constrained bridges are broken, and the unbound or brokengroups liberated as a volatile gas. By an alternative theory, both sidesreact, although delayed, to produce a constrained structure, which, uponcarbonization, liberates gaseous products that result in a hierarchicalstructure.

In some embodiments, a dione compound that is not encompassed by Formula(1) is excluded from the dione component, or from the precursorcomposition altogether. In other embodiments, a dione compound that isnot encompassed by Formula (2) is excluded from the dione component, orfrom the precursor composition altogether. In yet other embodiments, adione compound that is not encompassed by Formula (1) or (2) is excludedfrom the dione component, or from the precursor composition altogether.Some examples of dione compounds that may be excluded (and which are notencompassed by Formulas (1) and (2)) include, for example,malondialdehyde, succinaldehyde, glutaraldehyde, adipaldehyde,pimelaldehyde, suberaldehyde, sebacaldehyde, and terephthaldehyde. Instill other embodiments, one or more subclasses or specific types ofdione compounds, either from Formula (1) or (2) may be excluded from thedione component, or from the precursor composition altogether. In yetother embodiments, a mono-aldehyde or mono-ketone, such as formaldehyde,acetaldehyde, acetone, or furfural, is excluded from the precursorcomposition.

The acidic component in the precursor composition can be any acid strongenough to accelerate the reaction between phenolic and dione compounds.In some embodiments, the acid is a weak acid, such as an organic acid,such as acetic acid, propionic acid, or phosphoric acid. In otherembodiments, the acid is a strong acid, such as a mineral acid, such ashydrochloric acid, hydrobromic acid, hydroiodic acid, sulfuric acid, ora superacid, such as triflic acid. Depending on the type of acid andother conditions, the molar concentration of acid (per total precursorcomposition) can be, for example, at least 0.5 molar (i.e., 0.5 M), 0.6M, 0.7 M, 0.8 M, 1.0 M, 1.2 M, 1.5 M, 1.8 M, 2.0 M, 2.5 M, 3.0 M, 3.5 M,4.0 M, 4.5 M, 5.0M, or an acid concentration within a range bounded byany two of the foregoing values. The molar concentration values givenmay also be referred to in terms of molar equivalents of H⁺, or pH,wherein the pH for a strong acid generally abides by the formula pH=−log[H⁺], wherein [H⁺] represents the concentration of H⁺ ions.

In some embodiments, the molar amount of dione component is higher thanthe molar amount of phenolic component (i.e., molar ratio of dione tophenolic components is greater than 1). In such embodiments, the molarratio of dione to phenolic components may be precisely, about, or atleast, for example, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0,2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, or 3.0, or within a rangebounded by any two of these values. In other embodiments, the molaramount of dione component is less than the molar amount of phenoliccomponent (i.e., molar ratio of dione to phenolic components is lessthan 1). In such embodiments, the molar ratio of dione to phenoliccomponents may be precisely, about, or less than, for example, 0.9, 0.8,0.7, 0.6, 0.5, 0.4, 0.3, or 0.2, or within a range bounded by any two ofthese values. In other embodiments, the molar amount of dione componentis about the same as the molar amount of phenolic component.

Any one or more of the above components may or may not be dissolved in asuitable solvent. The solvent can be, for example, an organic polarprotic or non-protic solvent. Some examples of organic polar proticsolvents include alcohols, e.g., methanol, ethanol, n-propanol,isopropanol, ethylene glycol, and the like. Some examples of organicpolar non-protic solvents include acetonitrile, dimethylformamide,dimethylsulfoxide, methylene chloride, organoethers (e.g.,tetrahydrofuran or diethylether), and the like. In some embodiments, anysolvent, or any of the classes or particular types of solvents describedabove (except for water), may be excluded from the precursorcomposition.

In some embodiments, an orthoacetate, e.g., triethyl orthoacetate, isexcluded from the precursor composition. In other embodiments, a weakacid (i.e., having a pKa above −2), and particularly, the weak organicacids (e.g., p-toluenesulfonic acid or hypophosphorous acid), areexcluded from the precursor composition. In yet other embodiments, aphenol-formaldehyde resole or novolak resin (e.g., those of 500-5000M.W.) is excluded from the precursor composition.

In some embodiments, all of the precursor components, described above,are combined and mixed to form the precursor composition. The precursorcomposition can then be deposited by any suitable means known in the artto produce a film (i.e., coating) of the precursor composition on asubstrate. Some examples of solution deposition processes includespin-coating, brush coating (painting), spraying, and dipping. Afterbeing deposited, the precursor film is subsequently cured and thencarbonized.

In other embodiments, a multi-step process is employed in which aportion of the precursor components is first deposited to produce aninitial film, and the initial film subsequently reacted by the remainingcomponent(s) of the precursor composition. After all components havereacted to produce a precursor film, the precursor film is cured andthen carbonized. Additional steps may also be included. For example, amulti-step process may be employed wherein the templating component incombination with the phenolic component is first deposited by, forexample, applying (i.e., coating) said components onto a surface. Ifdesired, the initially produced film can be converted to a solid film byremoving solvent therefrom (e.g., by annealing). The produced film maythen be reacted with the dione component (e.g., by a liquid or vaporphase reaction) under acidic conditions to produce the polymerized (andoptionally, crosslinked) carbon precursor material. The resulting curedfilm can then be carbonized to produce the mesoporous carbon material.

The curing step includes any of the conditions, as known in the art,which promote polymerization, and preferably, crosslinking, of polymerprecursors, and in particular, crosslinking between phenolic andaldehydic or dione components. The curing conditions generally includeapplication of an elevated temperature for a specified period of time.However, other curing conditions and methods are contemplated herein,including radiative (e.g., UV curing) or purely chemical (i.e., withoutuse of an elevated temperature). In particular embodiments, the curingstep involves subjecting the polymer precursors or the entire precursorcomposition to a temperature of precisely, at least, or about, forexample, 50, 60, 70, 80, 90, 100, 110, 120, 130, or 140° C. for a timeperiod of, typically, at least 0.5, 1, 2, 5, 10, or 12 hours, and up to15, 20, 24, 36, 48, or 72 hours, wherein it is understood that highertemperatures generally require shorter time periods.

In particular embodiments, it may be preferred to subject the precursorsto an initial lower temperature curing step followed by a highertemperature curing step. The initial curing step may employ atemperature of about, for example, 50, 60, 70, 80, 90, or 100° C. (or arange between any of these), while the subsequent curing step may employa temperature of about, for example, 90, 100, 110, 120, 130, or 140° C.(or a range between any of these), provided that the temperature of theinitial curing step is less than the temperature of the subsequentcuring step. In addition, each curing step can employ any of theexemplary time periods provided above.

Alternatively, it may be preferred to gradually increase the temperatureduring the curing step between any of the temperatures given above, orbetween room temperature (e.g., 15, 20, 25, 30, or 35° C.) and any ofthe temperatures given above. In different embodiments, the gradualincrease in temperature can be practiced by employing a temperatureincrease rate of, or at least, or no more than 1° C./min, 2° C./min, 3°C./min, 5° C./min, 7° C./min, 10° C./min, 12° C./min, 15° C./min, 20°C./min, or 30° C./min, or any suitable range between any of thesevalues. The gradual temperature increase can also include one or moreperiods of residency at a particular temperature, and/or a change in therate of temperature increase.

The carbonization step includes any of the conditions, as known in theart, which cause carbonization of the precursor composition. Generally,in different embodiments, a carbonization temperature of precisely,about, or at least, for example, 300° C., 350° C., 400° C., 450° C.,500° C., 550° C., 600° C., 650° C., 700° C., 750° C., 800° C., 850° C.,900° C., 950° C., 1000° C., 1050° C., 1100° C., 1150° C., 1200° C.,1250° C., 1300° C., 1350° C., 1400° C., 1450° C., 1500° C., 1600° C.,1700° C., or 1800° C. (or a range therein) is employed for a time periodof, typically, at least 1, 2, 3, 4, 5, or 6 hours and up to 7, 8, 9, 10,11, or 12 hours, wherein it is understood that higher temperaturesgenerally require shorter time periods to achieve the same result. Ifdesired, the precursor composition, or alternatively, the carbonizedmaterial, can be subjected to a temperature high enough to produce agraphitized carbon material. Typically, the temperature capable ofcausing graphitization is a temperature of or greater than about 2000°C., 2100° C., 2200° C., 2300° C., 2400° C., 2500° C., 2600° C., 2700°C., 2800° C., 2900° C., 3000° C., 3100° C., or 3200° C., or a rangebetween any two of these temperatures. Preferably, the carbonization orgraphitization step is conducted in an atmosphere substantially removedof oxygen, e.g., typically under an inert atmosphere. Some examples ofinert atmospheres include nitrogen and the noble gases (e.g., helium orargon). Generally, for most purposes of the instant invention, agraphitization step is omitted. Therefore, other conditions thatgenerally favor graphitization (e.g., inclusion of catalytic species,such as iron (III) complexes) are preferably excluded.

In particular embodiments, it may be preferred to subject the precursorsto an initial lower temperature carbonization step followed by a highertemperature carbonization step. The initial carbonization step mayemploy a temperature of about, for example, 300, 350, 400, 450, 500,550, 600, 650, 700, 750, 800, 850, or 900° C. (or a range between any ofthese), while the subsequent carbonization step may employ a temperatureof about, for example, 500, 550, 600, 650, 700, 750, 800, 850, 900, 950,1000, 1050, 1100, 1200, 1250, 1300, 1400, 1450, 1500, 1600, 1700, or1800° C. (or a range between any of these), provided that thetemperature of the initial carbonization step is less than thetemperature of the subsequent carbonization step. In addition, eachcarbonization step can employ any of the exemplary time periods givenabove.

Alternatively, it may be preferred to gradually increase the temperatureduring the carbonization step between any of the temperatures givenabove, or between room temperature (e.g., 15, 20, 25, 30, or 35° C.) andany of the temperatures given above. In different embodiments, thegradual increase in temperature can be practiced by employing atemperature increase rate of, or at least, or no more than 1° C./min, 2°C./min, 3° C./min, 5° C./min, 7° C./min, 10° C./min, 12° C./min, 15°C./min, 20° C./min, 30° C./min, 40° C./min, or 50° C./min, or anysuitable range between any of these values. The gradual temperatureincrease can also include one or more periods of residency at aparticular temperature, and/or a change in the rate of temperatureincrease.

In particular embodiments, after combining the components of theprecursor composition, and before curing or carbonization, the solutionis stirred for a sufficient period of time (e.g., at least or about 1,2, 5, 10, 20, 30, 40, 50, 60, 90, or 120 minutes, or a range between anythese values) until a gel-like phase is formed, which is typicallyevidenced by an increased turbidity in the solution. The turbiditygenerally indicates formation of an ordered nanocomposite gel or solidthat has undergone a degree of phase separation from the liquid portionof the solution. If desired, stirring can be continued after the onsetof turbidity, such that the total amount of stirring time before curing,carbonization, or a phase-separation process is any of the exemplarytime periods given above, or a longer period of time, such as severalhours (e.g., at least or about 4, 5, 6, 7, 8, 10, or 12 hours) or days(e.g., at least or about 1, 2, 3, 4, 5, 10, 15, or 20 days), or a rangebetween of the foregoing exemplary periods of time.

After turbidity becomes evident, the phase-separated mixture can besubjected to conditions that cause the ordered nanocomposite gel orsolid to be substantially removed or isolated from the liquid portion.Any separation method can be applied herein. For example, the phases canbe separated by centrifugation. In different embodiments, thecentrifugation can be conducted at an angular speed of precisely, atleast, about, or up to, for example, 2000 rpm, 2500 rpm, 3000 rpm, 4000rpm, 5000 rpm, 6000 rpm, 7000 rpm, 8000 rpm, 9000 rpm, 9500 rpm, 10000rpm, 11000 rpm, 12000 rpm, or 15000 rpm, or a range between any of thesevalues, for a period of time of, for example, 0.1, 0.2, 0.5, 1, 2, 3, 4,5, or 6 minutes, wherein it is understood that higher angular speedsgenerally require less amounts of time to effect an equivalent degree ofseparation. Superspeed centrifugation (e.g., up to 20,000 or 30,000 rpm)or ultracentrifugation (e.g., up to 40,000, 50,000, 60,000, or 70,000rpm) can also be used. The gel or solid phase, once separated from theliquid phase, is then cured and carbonized in the substantial absence ofthe liquid phase according to any of the conditions described above forthese processes.

Particles of the porous carbon material can be produced instead of afilm. The particles can be produced by any suitable method, such as, forexample, the spray atomization techniques known in the art which alsoinclude a capability of heating at carbonization temperatures. Forexample, the precursor composition described above (typically, in acarrier solvent, such as THF or DMF) can be sprayed through the nozzleof an atomizer, and the particulates directed into one or more heatedchambers for curing and carbonization steps. Alternatively, a portion ofthe precursor composition (e.g., templating agent and one of the polymerprecursors, such as the phenolic component) may first be atomized andthe resulting particles annealed (i.e., dried) by suitable conditions;the resulting particles may then be exposed to the other polymerprecursor (e.g., dione component) and subjected to acidic conditions,followed by curing and carbonization steps.

The hierarchical porous carbon material may also be functionalized, asdesired, by methods known in the art for functionalizing carbon orgraphite materials. For example, the porous carbon material may benitrogenated, fluorinated, or oxygenated by methods known in the art.The porous carbon material may be nitrogenated, fluorinated, oroxygenated, by, for example, exposure of the porous carbon film, eitherduring or after the carbonization process, to, respectively, ammoniagas, fluorine gas, or oxygen gas under suitably reactive conditions. Inthe particular case of fluorination, the carbon material is typicallyplaced in contact with fluorine gas for a period of several minutes(e.g., 10 minutes) up to several days at a temperature within 20° C. to500° C., wherein the time and temperature, among other factors, areselected based on the degree of fluorination desired. For example, areaction time of about 5 hours at ambient temperature (e.g., 15-30° C.)typically results in fluorination of about 10% of the total carbon; incomparison, fluorination conducted at about 500° C. for two days resultsin about 100% fluorination of the total carbon. In particularembodiments, the degree of nitrogenation, fluorination, or oxygenationcan be about or at least 1%, 2%, 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%,80%, 90%, 95%, or 100%, or a range between any two of these values.

In another aspect, the invention is directed to a capacitivedeionization (CDI) device that includes the porous carbon material(described above) in one or two electrodes of the CDI device. Theinvention is also directed to a method for desalinating water byelectrically operating the CDI device. The invention is also directed toa method of energy storage by using the porous carbon material describedherein in a capacitive device, such as a battery, supercapacitor, orelectric double layer capacitor (EDLC).

The hierarchical porous carbon material described herein is included inat least one electrode of the CDI or related device (e.g., EDLC device).In one embodiment, at least one (or both, a portion, or all) of theelectrodes is constructed of the hierarchical porous carbon material,except perhaps for the current collector. In another embodiment, thehierarchical porous carbon material is in the form of a coating on asuitable base electrode material (or current collector). The baseelectrode material or current collector is often a conductive carbonmaterial, such as graphite or carbon paper. In yet another embodiment,the hierarchical porous carbon material is in the form of a layercovered by a layer of another porous material, such as a mesoporouscarbon material, carbon foam, or porous graphite. In some embodiments, atitanium sheet current collector is used. In other embodiments, acomposite material (e.g., activated carbon powder and a thermoplasticmaterial, such as PTFE) is used as the base electrode or currentcollector.

In some embodiments, the hierarchical porous carbon material describedherein, without admixture with another carbon material, is used as theelectrode or coated on a base electrode or current collector. In otherembodiments, the hierarchical porous carbon material described herein isadmixed with one or more other carbon materials (e.g., activated carbon,a mesoporous carbon, a carbon foam, or a carbon aerogel). When admixingis desired, the porous carbon material is typically in a particulateform, such as a powder.

A CDI device generally includes at least the feature of two porouselectrodes of opposite polarity spaced in such a manner that flowingliquid (typically water, or an aqueous solution containing water) makescontact with the electrodes. In some embodiments, the electrodes areseparated by an insulating material that permits the flow therethroughof water to be deionized by inclusion of flow channels in the insulatingmaterial. The insulating material includes means (e.g., spaces,channels, or pores) that permit the liquid to make efficient contactwith the porous electrodes. When operated (i.e., by applying a suitablevoltage bias across the electrodes), the CDI device removes salt speciesfrom the water by absorbing cationic species into the negatively chargedelectrode and anionic species into the positively charged electrode,similar to a capacitor, such as a supercapacitor or EDLC, both of whichare additional applications for the hierarchical porous carbon materialsdescribed herein. The base electrode material can be any suitableelectrically conductive material, including any of the substratematerials described above, provided the substrate material permits theCDI device to desalinate water. In particular embodiments, the baseelectrode material is porous.

The CDI device can have any of the features and designs known in theart. See, for example, U.S. Pat. No. 5,636,437, U.S. Pat. No. 5,776,633,U.S. Pat. No. 5,932,185, U.S. Pat. No. 5,954,937, U.S. Pat. No.6,214,204, U.S. Pat. No. 6,309,532, U.S. Pat. No. 6,778,378, U.S. Pat.No. 7,766,981, U.S. Pat. No. 7,835,137, U.S. Application Pub. No.2008/0274407, U.S. Application Pub. No. 2009/0141422, U.S. ApplicationPub. No. 2009/0305138, U.S. Application Pub. No. 2009/0320253, Jung, etal., Desalination, 216, pp. 377-385 (2007), R. W. Pekala, et al.,Journal of Non-Crystalline Solids, 225, pp. 74-80 (1998), and D.Carriazo, et al., J. Mater. Chem., 20, pp. 773-780 (2010), all of whichdescribe numerous features and designs in CDI, EDLC, and relateddevices, as well as numerous methods for fabricating electrodes in suchdevices, as well as methods of operating CDI, EDLC and related devices.The variations and designs of CDI devices, as well as methods ofmanufacture, and methods of their use, described in the foregoingreferences, are herein incorporated by reference in their entirety. Insome embodiments, one or more features described in said references areexcluded from the instant CDI device. Furthermore, in some embodiments,two electrodes are employed, while in other embodiments, more than two,or a multiplicity of electrodes (for example, miniaturized electrodes)are employed. In some embodiments, the electrodes are in a stackedarrangement, such as an alternating left-right arrangement to maximizeflow rate. In particular embodiments, the CDI device is a membranecapacitive deionization (MCDI) device by employing an anion-exchangemembrane coated on the anode and/or a cation-exchange membrane coated onthe cathode, wherein the anion- or cation-exchange membrane is generallypositioned between the flowing water and respective electrode. In otherembodiments, such exchange membranes are excluded from the device.

In other aspects, the hierarchical porous carbon materials describedherein are used as chromatography media, particularly for use in HPLC,and more particularly, for use in electrochemically modulated liquidchromatography (EMLC), as described, for example, in U.S. Pat. No.7,449,165, the contents of which are incorporated herein by reference intheir entirety.

Examples have been set forth below for the purpose of illustration andto describe certain specific embodiments of the invention. However, thescope of this invention is not to be in any way limited by the examplesset forth herein.

Example 1 Preparation of a Hierarchical Porous Carbon Film by ReactingPhloroglucinol and Glyoxal

Phloroglucinol, tetrahydrofuran (THF), and Pluronic F-127 were obtainedfrom Sigma-Aldrich. Ethanol (200 proof) was obtained from VWRScientific, and glyoxal was obtained from Alfa Aesar.

In a typical experiment, 1.15 g phloroglucinol (9.12 mmol) and 1.15 gPluronic F-127 were dissolved in 4.5 mL ethanol (200 proof) and 4.5 mLof 3M HCl. Once dissolved, 1.3 mL of 40 wt. % aq. glyoxal solution(11.33 mmol) was added and the mixture stirred. Phase separation wasobserved 20 minutes after glyoxal addition. The mixture was stirred foran additional 30 minutes after phase separation, and then the gel andsolvent were transferred to a centrifuge tube. The gel was separatedfrom the solvent by centrifugation at 9600 RPM for six minutes. Thesolvent was then decanted off the gel layer and 0.5 g THF and 2.0 gethanol (200 proof) was added. After mixing, the gel was cast onto glassPetri dishes and allowed to dry in a fume hood overnight. The gel wasthen cured at 353 K for 24 hours followed by carbonization at 1123 K for2 hours (2 K/min ramp rate) in a nitrogen atmosphere.

Example 2 Analysis of the Hierarchical Porous Carbon Material

Phloroglucinol is reported to react faster than resorcinol or phenolwith formaldehyde (see, for example, P. Xu, et al., Water Res., 2008,42, 2605-2617, and X. Q. Wang, et al., Langmuir, 2008, 24, 7500-7505).Although phloroglucinol is attractive for its potential in producingordered porous carbon materials, the increased reaction rate can lead toa disordered and non-hierarchical porous carbon, among other detrimentaleffects for the purposes of the instant invention. To obtain an orderedporous carbon, the fast reactivity of phloroglucinol has beencompensated by a slower reacting aldehyde than formaldehyde. Glyoxal isa slow reacting aldehyde, potentially due to the possible enoltautomerization, described above, that can stabilize a reactionintermediate structure and hinder further crosslinking. Therefore, basedsolely on condensation reactivity, the fast reacting phloroglucinol andslow reacting glyoxal were found herein to be a beneficial pairing.

Surface Area Analysis

Nitrogen sorption analysis was performed on a Micromeritics Tristar 3000at 77 K. Prior to measurement, the samples were degassed at 423 K underflowing nitrogen. The specific surface area was calculated using theBrunauer-Emmett-Teller (BET) equation utilizing the adsorption branch.The pore size distribution plot was derived from the adsorption branchof the isotherms using the Barret-Joyner-Halenda (BJH) method.

As shown in FIG. 1, nitrogen sorption isotherms with a hysteresis loopindicating the presence of mesopores were obtained from the carbonizedphloroglucinol-glyoxal polymer produced in Example 1. The surface areawas comparable to that of resorcinol-formaldehyde carbons synthesized bya similar method at 410 m²/g (see X. Q. Wang et al., 2008, Ibid.). Thenarrow (BJH) pore size distribution centered on 7.5 nm is indicative ofthe well-ordered templated structure (inset of FIG. 1).

Raman Spectroscopy Analysis

Raman measurements on the porous carbon produced in Example 1 werecollected with a Renishaw System 1000 microscope using a 632 nm He—Nelaser (25 mW power) and a 50× objective. Raman spectroscopy is widelyused to probe the amount of graphitic vs. amorphous carbon via two bandsthat have become the “fingerprint” regions for carbon materials. TheI(G) band identified as the graphitic carbon, is centered around 1600cm⁻¹ and is attributed to sp² carbon. The I(D) band identified withamorphous carbon is attributed to sp^(a) carbon. The Raman spectrum(FIG. 2) of the carbonized material displayed two features, a sharp bandcentered on 1600 cm⁻¹ and the second feature centered on 1330 cm⁻¹.These two features correspond to the graphitic (I_(G)=1600 cm⁻¹) anddisordered carbon (I_(D)=1330 cm⁻¹) structures associated with carbonmaterials. A shoulder on the I(D) band located near 1170 cm⁻¹ is alsoattributed to the disordered carbon structures.

Scanning Transmission Electron Microscopy (STEM) Analysis

Scanning transmission electron microscope (STEM) images were collectedon a Hitachi HD2000 STEM. Scanning transmission electron microscopy(STEM) was used to gain further insight into the porous structure of thecarbon produced in Example 1. As shown by the STEM images in FIG. 3, thecarbon possesses a hierarchical porosity. In particular, in addition tothe 7.5 nm mesopores, as also revealed by nitrogen adsorption analysis,larger pores with diameters up to 200 nm were present. While glyoxal wasnot expected to produce a hierarchical structure, the presence of thepores larger than 50 nm, observed by STEM microscopy, are suggestive ofa bimodal porous network. Previous work on hierarchical carbon ofteninvolves the decomposition of a secondary porogen, as occurs withspinodal decomposition, to create the secondary porous structure or theuse of hydrothermal techniques (see, for example, C. D. Liang, et al.,Chem. Mater., 2009, 21, 2115-2124; P. Adelhelm, et al., Adv. Mater.,2007, 19, 4012; D. Carriazo, et al., J. Mater. Chem., 2010, 20, 773-780;and Y. Huang, et al., Chem. Commun., 2008, 2641-2643). The benefits andadvantages of producing a hierarchical porous carbon material by afacile method at room temperature and without toxic formaldehyde aresignificant.

Example 3 Preparation of Electrodes Containing a Hierarchical PorousCarbon Film Produced by Reacting Phloroglucinol and Glyoxal

Graphite plates were used as dual current collector and electrodesupports for the carbon. The active area for the CDI electrode was 103.2cm² and was roughened to facilitate adhesion of the gel to the graphite.Phloroglucinol (8.00 g, 63.4 mmol) and Pluronic F-127 (8.00 g) weredissolved in 34 mL ethanol (200 proof) and 34 mL of 3M hydrochloricacid. Glyoxal (9.8 mL, 85.4 mmol) was added and the solution allowed tostir for 50 minutes. Phase separation was observed at 20 minutes afterglyoxal addition. After 50 minutes, the gel mixture was allowed to setfor 1-2 minutes to allow further phase separation from the solvent. Thesolvent was decanted and the gel spread onto the active area of thegraphite electrodes. The porous carbon-coated graphite electrodes wereallowed to dry overnight at room temperature, and then cured at 353 Kfor 24 hours. The plates were then carbonized at 1123 K under argon.Each graphite plate consisted of approximately 5.0 g of porous carbon inthe active area.

Example 4 Capacitive Deionization (CDI) Experiments

Capacitive deionization experiments were conducted using anelectrosorption cell that consisted of a pair of graphite electrodescoated with a hierarchical porous carbon, as described in Example 3. Aseparation distance between the two electrodes was maintained by using apolycarbonate sheet spacer (hollow at the center) of 6.4-mm thickness atthe center of the cell. The assembly of one-half of the electrochemicalcell followed this sequence: polycarbonate sheet endplate (9.5 mmthick), neoprene sheet gasket (1.6 mm thick), graphite electrode (3.2 mmthick) with the porous carbon coating, and neoprene sheet gasket (1.6 mmthick; hollow at the center). The distance between the currentcollectors was 9.6 mm, which is the same as the thickness of thepolycarbonate spacing (6.4 mm) plus the thickness of two neoprene gasketsheets (1.6-mm each). The distance between the material on the graphiteelectrodes depended on their thickness. The graphite plates wereconnected to a power supply (HP E3632A). The thickness of the porouscarbon film was approximately 2 mm.

The potential difference applied to the two electrodes was 1.2 V. Thispotential was applied 600 seconds after the data acquisition started,and led to an effective removal of ions without causing electrochemicalreactions and high current. Instant Ocean® (Aquarium Systems) solutionsof various concentrations in deionized water were used in capacitivedeionization experiments. In each experiment, the solution wascontinuously pumped through the electrosorption cell by a pump at a flowrate of 30 mL/min. The solution conductivity was monitored at the outletof the cell by using an electrical conductivity probe connected to ameter (Amber Science 3082). After the conductivity meter, the solutionwas collected by a beaker and then recycled through the cell by thepump. A volume of 100 mL was used in each experiment. The conductivitymeter and power supply were connected to a data acquisition system(National Instruments USB-6008) and data were stored in the hard-driveof a laptop computer.

Example 5 Capacitive Deionization (CDI) Results

Representative capacitive deionization results are shown in FIGS. 4A and4B. FIG. 4A shows CDI results for resorcinol-formaldehyde mesoporouscarbon-coated graphite of the art, as synthesized according to X. Q.Wang et al., 2008, Ibid. FIG. 4B shows CDI results forphloroglucinol-glyoxal hierarchical carbon-coated graphite, as producedand analyzed herein in accordance with Examples 3 and 4. The initialconcentration of Instant Ocean® was 3,967 ppm for the experimentpresented in FIG. 4A and 4,464 ppm for the experiment presented in FIG.4B. The final concentration was 2,569 ppm for the experiment presentedin FIG. 4A and 3,069 ppm for the experiment presented in FIG. 4B. Amaterial balance revealed that the mesoporous resorcinol-formaldehydecarbon-coated graphite in the experiment of FIG. 4A removed 146.8 mg ofsalt, while the phloroglucinol-glyoxal carbon-coated graphite in theexperiment of FIG. 4B removed 139.5 mg of salt. The results of theseexperiments were similar, except for the kinetics of ion uptake by theelectrodes. In the first experiment (FIG. 4A), within 1000 seconds, thesolution conductivity dropped by 0.19 mS; whereas in the secondexperiment (FIG. 4B), for the same period of time, the solutionconductivity dropped 0.67 mS. Hence, the initial slope of ion uptake bythe phloroglucinol-glyoxal carbon of the instant invention was more thanthree times the slope of the resorcinol-formaldehyde carbon of the art.

The similarity in the ion capacity is related to the similar pore sizesfound in the resorcinol-formaldehyde carbon material of the art andphloroglucinol-glyoxal carbon material produced herein. In turn, thesimilar pore sizes results predominantly from use of the same structuretemplate, i.e., Pluronic F127. XPS analysis of the carbon materials hasindicated similar surface functionalities between the carbon samples,suggesting the difference in ion uptake and kinetics is not due todifferent surface functionalities. However, the three-times (3×)increase in ion uptake kinetics is most likely due to the hierarchicalstructure of the instant phloroglucinol-glyoxal carbon. Therefore, ithas been shown that the hierarchical porous carbon produced herein isadvantageous over resorcinol-formaldehyde carbon materials of the artfor capacitive deionization.

In conclusion, these Examples demonstrate that phloroglucinol reactswith glyoxal in the presence of the triblock copolymer Pluronic F127 toform a hierarchical porouscarbon material with an ordered, well-definedmesoporous component. This is the first known reported synthesis of a“hard carbon” based on glyoxal, as well as the templating of aphenolic-glyoxal resin. The hierarchical porosity in the porous carbonmaterials produced in the above Examples has been found to containmesopores up to 200 nm, as well as mesopores of 7.5 nm. Moreover, the7.5 nm mesopores are highly uniform in size. Significantly, thehierarchical structure has been provided by the crosslinking reagent(i.e., dione) and not by the use of a secondary porogen undergoingspinodal decomposition, as commonly relied upon in the art. Thus, a newand superior methodology for synthesizing hierarchical carbon materialshas herein been described wherein the crosslinking reagent, as opposedto the templating agent, exerts a dominant effect on the porousstructure. Moreover, as demonstrated above, capacitive deionizationtests indicate that the hierarchical porous carbon material producedherein is a better CDI electrode than that of mesoporousresorcinol-formaldehyde carbon materials of the art for removal of saltsfrom brackish water due to faster ion uptake kinetics.

While there have been shown and described what are at present consideredthe preferred embodiments of the invention, those skilled in the art maymake various changes and modifications which remain within the scope ofthe invention defined by the appended claims.

What is claimed is:
 1. A capacitive deionization device comprised offirst and second electrodes and a space between said electrodes for theflow of water, wherein at least one of said first and second electrodesis comprised of a porous carbon material possessing a hierarchicalporosity comprised of mesopores and macropores, wherein said mesoporeshave a size in the range of 2-50 nm and said macropores have a size ofat least 75 nm.
 2. The capacitive deionization device of claim 1,wherein said mesopores have a size in the range of 2-20 nm and saidmacropores have a size in the range of 100-500 nm.
 3. The capacitivedeionization device of claim 1, wherein said electrodes are separated byan insulating material, wherein said insulating material permits theflow therethrough of water to be deionized while permitting contact ofthe water with each of said first and second electrodes
 4. Thecapacitive deionization device of claim 1, wherein at least a portion ofsaid porous carbon material is amorphous.
 5. The capacitive deionizationdevice of claim 1, wherein at least one of said electrodes is comprisedof said porous carbon material possessing a hierarchical porositydisposed as a film on a base electrode substrate material.
 6. Thecapacitive deionization device of claim 5, wherein said film has athickness of up to 5 millimeters.
 7. The capacitive deionization deviceof claim 5, wherein said film has a thickness of up to 100 microns. 8.The capacitive deionization device of claim 5, wherein said baseelectrode substrate material is comprised of an electrically conductivecarbon material.
 9. The capacitive deionization device of claim 8,wherein said electrically conductive carbon material is graphite.
 10. Amethod for the desalination of water, the method comprising flowingwater in need of desalination through a capacitive deionization devicewhen the electrodes of said capacitive deionization device are inelectrical operation configured as anode and cathode, said capacitivedeionization device comprised of first and second electrodes and a spacebetween said electrodes for the flow of water, wherein at least one ofsaid first and second electrodes is comprised of a porous carbonmaterial possessing a hierarchical porosity comprised of mesopores andmacropores, wherein said mesopores have a size in the range of 2-50 nmand said macropores have a size of at least 75 nm.
 11. The method ofclaim 10, wherein said mesopores have a size in the range of 2-20 nm andsaid macropores have a size in the range of 100-500 nm.
 12. The methodof claim 10, wherein said electrodes are separated by an insulatingmaterial, wherein said insulating material permits the flow therethroughof water to be deionized while permitting contact of the water with eachof said first and second electrodes
 13. The method of claim 10, whereinat least a portion of said porous carbon material is amorphous.
 14. Themethod of claim 10, wherein at least one of said electrodes is comprisedof said porous carbon material possessing a hierarchical porositydisposed as a film on a base electrode substrate material.
 15. Themethod of claim 14, wherein said film has a thickness of up to 5millimeters.
 16. The method of claim 14, wherein said film has athickness of up to 100 microns.
 17. The method of claim 14, wherein saidbase electrode substrate material is comprised of an electricallyconductive carbon material.
 18. The method of claim 17, wherein saidelectrically conductive carbon material is graphite.